Remote sensing involves collecting information about objects without physical contact. It was first defined in the 1960s and the first earth observation satellite, Landsat-1, was launched in 1972. Remote sensing uses sensors on airborne and spaceborne platforms to detect electromagnetic radiation reflected or emitted from the object of interest. Common platforms include aircraft, balloons, and satellites. Satellites provide global coverage and frequent revisits. Remote sensing data has various applications such as agriculture, forestry, and soil mapping.

2. Remotesensing
The technical term Remote sensing
was first used in the united states in
the 1960 .
It simply referred collection of
information an object without coming
into physical contact .
Landset-1 - first earth observation
satellite was launched in the 1972.

3. REMOTE SENSING
 Remote sensing is defined as the
technique of obtaining
information about objects
through the analysis of data
collected by special instruments
that are not in physical contact
with the object of investigation.
 The information needs a physical
carrier to travel from the object
/events to the sensors through an
intervening medium.

4. Conti……
 The electromagnetic
radiation is normally
used as an information
carrier in remote
sensing.
 The output of a remote
sensing system is
usually an image
representing the scene
being observed.

5. Drawbacks of traditional methods
1. Data collection cannot be done throughout the
year due to unfavorable weather condition.
2. Data collection from inaccessible areas is not
possible.
3. Data collection through traditional method is
time consuming and there is wide gap between
data collection and its possible utilization.

6. Advantage of remote sensing
1. Relatively cheap and rapid method of acquiring
up to data information over a large geographical
area.
2. It is only practical way to obtain data from
inaccessible region like Antarctica , Amazonia.
3. The process of data acquisition and analysis is
faster.
4. Satellite data are received periodically and helps
in updating the information and monitoring the
change at short intervals.

7. Conti……
1. These have unique capability of recording
data in visible as well as invisible parts of
electromagnetic spectrum.
2. The data are unbiased record of the objects.
3. The data are collected an a permanent basis

9. Fundamentalsofremotesensing
 Electromagnetic remote sensing of earth resources
involves the two basis processes viz.
1. Data acquisition
2. Data analysis

11. The elements of data acquisition
process are :-
1. Energy sources
2. Propagation of energy through the atmosphere
3. Energy interaction with earth surface features
4. Re- transmission of energy through the
atmosphere
5. Air-borne and / or space borne sensors
6. Generation of sensor data in pictorial and / or
digital form

12.  Energy source :- the first requirements for remote
sensing is to have an energy source which illuminates
or provides electromagnetic energy to the target of
interest
 Propagation of energy through the
atmosphere :- as the energy travels from its
sources to the target , it will come in contact with and
interact with the atmosphere it passes through . This
interaction may take place a second time as energy
travels from the target to the sensor.
 Energy interaction with earth surface features:- it
interacts with the target depending on the properties
of both the target and the radiation

13.  Re- transmission :- the energy recorded by
the sensor has to be transmitted, often in
electronic form .
 Air-borne and / or space borne sensors :- it
use to collect and record the electromagnetic
radiation
 Generation of sensor data in pictorial and /
or digital form :- the energy recorded by the
sensor has to be transmitted, often in electronic
form, to a receiving and processing station where
the data are processed into an image (hardcopy /
digital)

14. Data analysis
 The processed image is interpreted, visually
and / or digitally or electronically , to extract
information about the target which was
illuminated

15. Type of remote sensing
1. Active remote sensing
2.Passive remote sensing

16. 1. Active remote sensing :- the use of season that
deduct reflected responses from object that are
irradiated from artificially generated energy
sources such as Radar.
2. Passive remote sensing :- The use of season
that deduct the reflected or emitted
electromagnetic radiation natural sources

18. Remote sensing platforms

20. Air borne platforms :- e.g. Balloons
, aircraft .
Balloons :- these are
designed and used for
specific projects.Through
the use of balloons is
commonly restricted by
meteorological factors
such as wind velocity ,
direction etc.

22. Aircraft
 Aircraft are commonly
used as remote sensing
platforms for obtaining
aerial photographs.
They are considered
useful for regional
coverage and large
scale mapping.

25.  Space borne plate forms i.e. satellites have proved
to be of vital use in natural mapping
meteorological and communication application .
 Satellites are free flying orbiting vehicles, whose
motion is governed by the gravity, and
atmosphere .

26.  Broadly satellites can be grouped under two
categories upon the type of orbits in which they
move.
1. Geo- stationary satellites
2. Sun- synchronous satellites

27. Geo-stationarysatellites
1. The orbit in which these satellites move is
called geo- stationary or geosynchronous
orbit .
2. These satellites are placed in an orbit at a
distance of 36000 km above the equators.
3. At this altitude, the orbital speed of the
satellite is same as that of earths rotation
speed and therefore the is satellite appears to
be stationary with respect to earth’s
movements.
4. Example :- GOES (USA) and INSAT (India)

28. Types of Satellites
Geostationary Satellites
A geostationary satellite is one of the satellites which is
getting remote sense data and located satellite at an
altitude of approximately 36000 kilometres and directly
over the equator.
Image Source: cimss.ssec.wisc.edu

29. 1. Satellites provide global coverage with high
resolution.
2. Such data is primary use for application in
resources survey and monitoring
3. The move is a low earth orbit at 800-1000km
altitude over a or near the north and south pole
the orbit is known as polar or sun synchronous
orbit, coinciding with the plan of the sun.
4. E.g.. LANSAT(USA),SPOT(French) and
IRS(INDIA) series are group under this category.

30.  This sensor converts these radiation into electrical
signals and presents it in a form suitable for
obtaining information about the land / earth
resource as used by an information gathering
systems
 The specific parameters of sensors are
1. Spatial resolution
2. Spectral resolution
3. Radiometric resolution
4. Temporal resolution

31. Spatial Resolution
 Dimensions of the smallest object or
minimum detectable area which can be
resolved by the sensor
 Large area covered by a pixel means low
spatial resolution and vice versa
Remote Sensing & GIS Applications Directorate

32. Remote Sensing & GIS Applications Directorate
High vs. Low?
Spatial Resolution
Source: Jensen (2000)

33. Remote Sensing & GIS Applications Directorate

34. Spectral Resolution
Remote Sensing & GIS Applications Directorate

35. Radiometric Resolution
 Radiometric Resolution refers to the smallest
change in intensity level that can be detected by
the sensing system.
 The number of gray level / values which a sensor
can difference between black and white.
 The more the grey levels, the better the
radiometric resolution.
Remote Sensing & GIS Applications Directorate

36. Remote Sensing & GIS Applications Directorate
Radiometric Resolution
1023
6-bit range
0 63
8-bit range
0 255
0
10-bit range
2-bit range
0 4

37. Temporal Resolution
Frequency at which images are recorded/ captured
in a specific place on the earth.
The more frequently it is captured, the better or
finer the temporal resolution is said to be
For example, a sensor that captures an image of an
agriculture land twice a day has better temporal
resolution than a sensor that only captures that
same image once a week.
Remote Sensing & GIS Applications Directorate

38. Remote Sensing & GIS Applications Directorate
Temporal Resolution
Time
July 1 July 12 July 23 August 3
11 days
16 days
July 2 July 18 August 3

39.  Based on energy sources ,
sensors are classification as
follows
 an active
sensors operates by
emitting its own energy
which is needed to direct
the various phenomena
e.g. RADAR , camera with
flash gun
 the
operation of passive sensors
is dependent on existing
sources of energy like sun

40.  Aerial photography is the taking of photographs of
the ground from an elevated position. Usually the
camera in not supported by a ground – based
structure .
 Platforms for aerial photography include
helicopters, rockets, pigeons , balloons , parachutes.
 Aerial photography was first practiced by the
French photographer and balloonist Gaspard – Felix
Tournachon known as “Nadar” in 1858

42. Aerial photography
photography taken from the air with
the camera pointing vertically or with an
angle downwards at the time of exposure.

43. Satellite remote sensing
 Remote sensing data in unique in it is ability to
provide a synoptic view of large area and the
capability to repetitively cover the same area
after a regular interval.
 The data provides information for a variety of
application , such as agriculture , forestry, soil
mapping , hydrology etc.

44. Sa
Satellite imagery consists of
photographs from which
collected by satellites.
Image Source: www.wonderwhizkids.com
Image Source: www.loneotaku.net
Japan Satellite View

45. Remote sensing institutes in
India
 NRSA(National Remote Sensing Agency),
Hyderabad :- is mainly responsible for acquisition
processing and dissemination of satellite / aerial data
processing and dissemination of satellite / aerial data and
training the personnel in various application techniques.
 The SAC (SpaceApplication Centre),Ahamedabad and the
ISRO (Indian Space Research Organisation), Bangalore are
responsible for the design and launching of sensors and
platforms, including satellite launch vehicles.
